A special kind of inventory are buffers, which you can also call temporary inventory. Dirty clothes are a good example for this type of inventory. You need to collect it, until you have enough to fill the washing machine. So far, it is unavoidable waste. The picture changes if you collect dirty clothes for weeks before cleaning them.Then you have an avoidable buffer waste.
In the production of goods such buffers usually exist whenever parts or partially finished goods are collected and stored, until they can be used.